The present invention relates to a device for the elimination of trimmings of rolls or logs of ribbon-like material, in particular which can be connected to a cropper machine.
It is well known that to produce rolls or similar of kitchen towel and/or toilet tissue rolls of paper are first formed wound on logs of a pre-selected diameter and a certain height. Subsequently, the single rolls must be cut to size ready for distribution and direct final use by the consumer.
Currently, these finished rolls are cut to a predetermined size by specific cropper machines which receive, for example, a series of logs and cut them into a plurality of shorter rolls in succession, each to the exact dimensions required. This operation on cropper machines, generally performed by rotating blades, leads to the creation, on a log or roll that is fed step by step, of a plurality of portions of the required size.
Nonetheless, both at the top end of each log or roll and at the tail end portions, which are unusable, are produced in the form of crop ends of a limited length. Moreover, a small core portion, also unusable, may also project from these portions and, therefore, both of them must be eliminated. Furthermore, these crop ends or trimmings of the rolls must be eliminated during evacuation of the rolls cut to size to in order not to obstruct packaging.
The presence of trimmings or crop ends could in fact also cause the packaging machine to block, not to mention packages in which the number of usable rolls could be incorrect due to the presence of these crop end rolls.
Complicated devices have been designed to allow trimmings or crop ends to be eliminated by suction of the rolls cut to the correct size advancing one after another, with crop ends advancing towards an opening, inside which the advancing trimmings or top and tail crop ends, coming from the cropper machine, fall.
These devices, although operating very well and in an essentially correct manner, determine a complicated machine design (suction, releases, synchronization, etc.). Moreover, adjustment must be performed between all the additional parts required both for suction of the rolls and transport of these.
The suction, which acts on the external part of the advancing roll, may also cause external roughening and damage to the product, and subsequently a final external appearance that is not entirely satisfactory.
A further example of a known device for the elimination of trimmings comprises an opening connected to which are two retractable surfaces that open and/or close it as a function of the cut product being conveyed. In fact, this envisages a retractable surface that closes the opening once the top trimming has passed and a retractable surface that operates when the tail trimming arrives, or when rolls cut to the correct size start to pass. In any case, one of the retractable surfaces keeps the opening closed when the rolls cut to size pass, allowing these to advance towards packaging.
This device also operates well, although it can cause problems related to perfectly synchronised movement between the two retractable surfaces and the conveyors to feed the rolls and crop ends in succession.
Moreover, correlation of the movements between the two retractable surfaces and advance of the rolls and crop ends can cause some problems of adjustment with possible jamming.
An object of the present invention is to produce a device for the elimination of the trimmings of rolls or logs of ribbon-like material, in particular which can be connected to, and at the outlet of, a cropper machine, which solves the technical problems set down above.
Another object is to produce a device for the elimination of the trimmings of rolls or logs of material in strips which allows correct elimination of the top and tail trimmings of the initial logs or rolls.
Yet another object is to produce a device for the elimination of the trimmings of rolls or logs of material in strips which is extremely simple to manufacture and easy to use.
Yet another object is to produce a device for the elimination of the trimmings of rolls or logs of material in strips which can keep pace with the high operating rates of the cropper machine, although having a simple structure and requiring very few synchronizations.
These objects according to the present invention are attained by producing a device for the elimination of the trimmings of rolls or logs of material in strips, in particular which can be connected to a cropper machine, as set down in claim 1.
Further characteristics of the invention are set down in the subsequent claims.